Name-address management generally includes issues such as name-to-address resolution and name-address registration. Name-to-address resolution is a procedure by which a “name” of a network resource, e.g., a network node, is resolved or translated into a routable network address, i.e., a location in the network topology. Name-address registration is the corresponding registration procedure by which the name and the assigned network address of the resource are registered in the network. The name of the resource is normally known to users and typically also stays the same over relatively long periods of time.
Traditional networking architectures for the Public Switched Telephone Network (PSTN) or Internet solve the problem of connecting terminals or hosts (which can be considered as “boxes”) in order to support a specific application such as telephony or WWW. To this end, traditional naming and addressing schemes employ host or network centric identities such as E.164 numbers for telephony, or Internet Protocol (IP) addresses and Uniform Resource Locators (URLs) for the Internet. However, the end user is typically interested in reaching a destination object that sits behind or within the box, such as a human being or a file, rather than communicating with the box itself. As the destination objects move to new boxes, box or network dependent identities of these objects must be updated. For example, it is an everyday experience that a person cannot be reached at the phone number registered in some semi-static directory because that directory does not track the phone that she is momentarily close to. Or a web link is broken because the target data object has been moved to another location. To address this class of problems, box-independent addressing schemes such as Telephone Number Mapping (ENUM), Session Initiation Protocol (SIP) names, and Uniform Resource Identifiers (URIs) have been developed. Using a presence or mobility mechanism, box-independent names of a destination object can then be mapped to the address of the box where the destination object is currently located. Likewise, inventory systems are used to track specific objects to a specific location.
In addition, it is quite common that mobile objects travel within or in association with other mobile objects. For example, a person may travel in association with a mobile phone that may be associated with a personal area network that may be associated with a vehicular network. Consider, for example, a person using a laptop with a Wireless Local Area Network (WLAN) who is working onboard a train that has Internet connectivity. To reach this person, three separate mobility-related functions must be used: 1) a presence function that binds the person to the laptop, 2) a mobility function that binds the laptop to a specific IP address on the train, and 3) a mobility function for the train.
Another example is a piece of merchandise that travels in a container that travels on a ship. For this case a separate inventory system would be used with little in common with the functions for personal and host mobility described in the previous example.
The Domain Name System (DNS) stores and provides information associated with domain names in a distributed database in networks such as the Internet. The DNS associates domain names with many types of information, but most importantly it provides the IP address for a given domain name. DNS makes it possible to associate easy-to-remember domain names (such as ericsson.com) with hard-to-remember IP addresses. DNS is suitable for resources that rarely change their location, but is not adapted for mobility. RFC 2136 describes “Dynamic Updates in the Domain Name System” in the hope of providing better support for rapid updates of DNS, but it is still far from being suitable for keeping track of roaming resources such as mobile phones and their users.
When routing protocols for the Internet and other fixed networks were initially created, hosts were not expected to move around. Therefore, hosts are usually named by their point of attachment to the network, e.g., IP addresses. Examples of such routing protocols include RIP, IS-IS, OSPF, BGP and PNNI. They are all well established technologies but have limited support for mobility and have convergence problems when network topologies change rapidly.
Traditionally, applications use IP-addresses in a way that does not allow them to change during an on-going session. To allow hosts to move without changing their IP-addresses (at least from an application perspective) mobility solutions in IP networks, such as Manet (ad hoc networks), Network Mobility (NEMO), and Mobile IP have been developed. But these are fairly complex solutions since they adapt a technology intended for fixed networks to new mobility requirements. In addition, there is a multitude of inventory systems for various classes of objects, such as library books or pieces of merchandise. Each system and mechanism is optimized for its specific class of objects. For example, mobile IP is optimized for mobility of IP boxes, SIP supports personal mobility, inventory systems handle mobility of goods, etc. Due to the diverse technologies employed in this field, it is hard to achieve synergies between the systems and mechanisms used for the different classes of mobile objects.
The Host Identity Protocol (HIP) provides a method of separating the end-point identifier and locator roles of IP addresses. It introduces a new Host Identity (HI) name space based on public keys. The public keys are typically self-generated. The HIP separation can be used to provide end-to-end connectivity over different locator domains. Even still, routing protocols under development cater to mobility of individual hosts (nodes) but do not adequately address the problems relating to mobile networks (MNs). A mobile network includes a group of many mobile hosts or other objects that move together as a group. Mobile network examples include networks located in any type of mobile vehicle, e.g., in a train, airplane, bus, ship, subway, etc., but are not limited to vehicles. All that is required is that the group of mobile objects, hosts and routers move substantially together at substantially the same time. Also, a communication satellite carrying a router is another example of a mobile network that dynamically attaches to ground stations, other communication satellites, and hosts or mobile phones. A particular mobility problem associated with mobile networks is a potentially huge number of registration or other location updates that need to be signalled and processed whenever the mobile network changes location. Such a move may cause an “update storm.”
Consider for example a Public Land Mobile Network (PLMN) type of system like GSM and 3G cellular networks. Mobile host name resolution is handled via a Home Location Register (HLR) and the Visited Location Register (VLR). When a mobile host is called, a phone number (MS-ISDN) is resolved via the VLR and HLR into a corresponding E.164 address that allows the call to be routed to the mobile host, if the mobile host with the MS-ISDN has registered its current location area with the VLR. Local mechanisms are used to route the call to the specific cell in the location area in which the mobile host is currently located.
The HLR and VLR have overall good performance and security support regarding name resolution in cellular systems. But they are closely linked to the E.164 address structure and as such do not provide an open architecture for other and/or arbitrary name and address spaces. Moreover, this approach to registering a host with a centralized location register like the HLR/VLR does not function well with mobile networks. The problem is particularly acute when a large mobile network with many subnetworks or hosts roams and requires registration update signalling for every one of its subnetworks and/or hosts—a good example of an “update storm” mentioned above.
In dynamic DNS, when such a mobile network roams, each host in the mobile network must have its DNS record updated. For that situation, mobile IP requires that all home agents having hosts in the mobile network be updated. RFC 3963 describes the IETF Network Mobility (NEMO) basic support protocol which enables mobile networks to attach to different points in the Internet. The protocol is an extension of mobile IPv6 and allows session continuity for every node in the Mobile Network as the network moves. It also allows every node in the Mobile Network to be reachable while mobile around. But NEMO's distributed solution suffers from what is called “pinball routing,” where all internetwork traffic must be routed between every mobility agent that has an associated mobile node or network in the path towards the destination host. As a result, tunnelling overhead accumulates per radio hop, and there are potential latency problems when several mobility agents are located at different continents, i.e., x-ogonal routing instead of triangular routing.
Thus none of the existing systems is designed to handle the nested mobility problem where mobile objects travel in association with other mobile objects. The NEMO solution described above is designed to handle nested mobility of networks and hosts, but not for mobile objects in general. Existing systems for the handling of digital objects, such as the Handle System for naming and accessing digital objects (RFC 3650) do not address the issue of updating the locator of a mobile object in a scalable fashion.